Process for the manufacture of 1,4-dicyanonaphthalenes

ABSTRACT

The present invention provides a new process for the manufacture of 1,4-disubstituted bicyclic or tricyclic compounds by reacting a 1,2-bis-cyanomethyl-benzene or 2,3-bis-cyanomethyl-naphthalene with glyoxal in the presence of a base and a solvent as well as new 1,4-disubstituted bicyclic compounds.

This is a division of application Ser. No. 629,180, filed on Nov. 5,1975, now U.S. Pat. No. 4,011,261.

The present invention provides a process for the manufacture of1,4-disubstituted bicyclic or tricyclic compounds and also provides new1,4-disubstituted bicyclic or tricyclic compounds.

Processes for the manufacture of 1,4-dicyanonaphthalenes which areunsubstituted in 2- and 3-position have already been disclosed in theliterature. The disadvantage of these processes is that the end productscan only be obtained by means of an alkali cyanide or alkaliferrocyanide melt which is effected at high temperatures with greatdifficulty, or from 1,4-dihalonaphthalenes which are not readilyaccessible. Such processes are described, for example, in A. 153, 309;B. 55, 120; J. Chem. Soc. 1936, 1739-44, or Monatsch. Chem. 83, 865-69,1952.

U.S. Pat. No. 3,652,667 describes the manufacture ofnaphthalene-1,4-dicarboxylic acid by oxidation of1-methyl-4-acetylnaphthalene with excess alkali dichromate at elevatedtemperature and under pressure. In this process,1-methyl-4-acetyl-naphthalene must be manufactured from1-methyl-naphthalene and acetyl chloride by a Friedel-Crafts reaction.The disadvantages of this process are that the oxidation is difficult toperform, the starting materials are hard to obtain, and the use ofsubstantial excesses of alkali dichromates creates ecological problems.

The present invention is based on the surprising observation that it ispossible to obtain 1,4-disubstituted bicyclic or tricyclic compoundswhile avoiding these disadvantages.

The present invention provides in the first instance a process for themanufacture of 1,4-dicyano-substituted bicyclic or tricyclic compoundsof formula ##STR1## wherein R₁ represents hydrogen, halogen, alkyl,alkoxy, carboxy, carbalkoxy, --CONR₅ R₆, wherein each of R₅ and R₆independently represents hydrogen or alkyl, or together they complete a5- or 6-membered heterocyclic ring, sulpho, --SO₂ NR₅ R₆, wherein R₅ andR₆ are as defined hereinbefore, alkylsulphonyl, arylsulphonyl, cyano,nitro, or together with R₂ completes a 6-membered aromatic ring orrepresents the methylenedioxy radical, R₂ represents hydrogen, halogen,alkyl, alkoxy, carboxy, carbalkoxy, --CONR₅ R₆, wherein R₅ and R₆ are asdefined hereinbefore, alkylsulphonyl, nitro, or together with R₁completes a 6-membered aromatic ring or represents the methylenedioxyradical, R₃ represents hydrogen, halogen, or alkyl, and R₄ representshydrogen, halogen or alkyl, which process comprises reacting ano-xylylene dicyanide of formula ##STR2## wherein R₁, R₂, R₃ and R₄ areas defined hereinbefore, with glyoxal in the presence of a base and asolvent at temperatures below 50° C.

The reaction is carried out, for example, at temperatures between -20°and +40° C, preferably between 0° and 30° C.

Suitable halogens are fluorine, chlorine and bromine, preferablychlorine. Alkyl, alkoxy and carbalkoxy radicals R₁, R₂, R₃ and R₄contain 1 to 18, preferably 1 to 6, carbon atoms. The akyl radicals R₅and R₆ and alkylsulphonyl radicals contain preferably 1 to 4 carbonatoms. A suitable arylsulphonyl radical is in particular thephenylsulphonyl radical.

Carboxy is to be understood as meaning the radical --COOM and sulpho theradical --SO₃ M, wherein M represents hydrogen or a salt-forming cation,such as that of sodium, potassium, calcium, barium or magnesium, andalso that of ammonium which is unsubstituted or substituted by alkyl orhydroxyalkyl of 1 to 4 carbon atoms. Besides hydrogen, M preferablyrepresents the potassium and sodium cation.

Suitable bases are inorganic and organic compounds, for example those oflithium, sodium, potassium, rubidium, cesium or ammonium, for examplehydroxides and alcoholates thereof, or tertiary amines, such as lithium,sodium or potassium hydroxide, sodium or potassium methylate, sodium orpotassium ethylate, triethylamine or pyridine.

Suitable solvents are aprotic and protic solvents, preferablywater-miscible organic solvents, for example methanol, ethanol,isopropanol, butanols, dioxan and dimethyl formamide.

The reaction is advantageously carried out in an anhydrous organicsolvent, preferably one in which the base is partially or completelysoluble.

The glyoxal used as starting material can be used either in the form ofits ordinary commercially available aqueous solution, e.g. 30% or 40%aqueous solution, or in the form of a compound that liberates glyoxalunder the reaction conditions, for example trimeric and polymericglyoxal, glyoxal bisulphite, glyoxal sulphate and glyoxal acetals.

Within the scope of this first feature of the invention, an interestingprocess is that for the manufacture of 1,4-dicyano-substituted bicyclicor tricyclic compounds of the formula ##STR3## wherein R₁ ' representshydrogen, halogen, alkyl, alkoxy, carboxy, carbalkoxy, --CONR₅ R₆,wherein each of R₅ and R₆ independently represents hydrogen or alkyl ortogether they complete a 5- or 6-membered heterocyclic ring,alkylsulphonyl, arylsulphonyl, cyano, nitro, or together with R₂ 'completes a 6-membered aromatic ring or represents the methylenedioxyradical, R₂ ' represents hyrogen, halogen, alkyl, alkoxy,alkylsulphonyl, or together with R₁ ' completes a 6-membered aromaticring or represents the methylene dioxy radical, and R₃ and R₄ are asdefined hereinbefore, which comprises reacting an o-xylene dicyanide offormula ##STR4## wherein R₁ ', R₂ ', R₃ and R₄ are as definedhereinbefore, with glyoxal.

A preferred process is that for the manufacture of1,4-dicyano-substituted bicyclic or tricyclic compounds of formula##STR5## wherein R₁ " represents hydrogen, halogen, alkyl,alkylsulphonyl, arylsulphonyl, or together with R₂ " completes a6-membered aromatic ring, R₂ " represents hydrogen, halogene, alkyl,alkylsulphonyl, or together with R₁ " completes a 6-membered aromaticring, R₃ represents hydrogen, halogen, or alkyl, and R₄ representshydrogen, halogen or alkyl, which comprises reacting an o-xylylenedicyanide of formula ##STR6## wherein R₁ ", R₂ ", R₃ and R₄ are asdefined hereinbefore, with glyoxal.

A preferred process is also that for the manufacture of1,4-dicyano-substituted bicyclic or tricyclic compounds of formula##STR7## wherein R₁ '" represents hydrogen, halogen, alkyl, or togetherwith R₂ '" completes a 6-membered aromatic ring, R₂ '" representshydrogen, halogen, alkyl, or together with R₁ '" completes a 6-memberedaromatic ring, R₃ ' represents hydrogen or halogen, R₄ ' representshydrogen or halogen, which comprises reacting an o-xylylene dicyanide offormula ##STR8## wherein R₁ '", R₂ '", R₃ ' and R₄ ' are as definedhereinbefore, with glyoxal, and for the manufacture of1,4-dicyano-substituted naphthalanes of formula ##STR9## wherein R₁ ""represents hydrogen, halogen or alkyl, R₂ "" represents hydrogen,halogen or alkyl, and R₃ ' represents hydrogen or halogen, whichcomprises reacting an o-xylylene dicyanide of formula ##STR10## whereinR₁ "", R₂ "" and R₃ ' are as defined hereinbefore, with glyoxal.

A particularly preferred process is that for the manufacture of1,4-dicyano-substituted naphthalenes of formula ##STR11## wherein R₁^(v) represents hydrogen or halogen and R₃ ' represents hydrogen orhalogen, which comprises reacting an o-xylylene dicyanide of formula##STR12## wherein R₁ ^(v) and R₃ ' are as defined hereinbefore, withglyoxal.

Within the scope of formulae (1) to (12), preferred compounds are thosewherein one of the four symbols R₁, R₂, R₃ or R₄, or one of the symbolsderived therefrom, represents hydrogen. Of particular importance arecompounds wherein three of these symbols represent hydrogen.

The most preferred process is that for the manufacture of1,4-dicyanonaphthalene of formula ##STR13## wherein o-xylylene dicyanideof formula ##STR14## is reacted with glyoxal.

The o-xylylene dicyanides used as starting materials can be obtainedvery easily and in very good yields from the corresponding o-xylylenedihalides by reaction with alkali cyanides. For example, o-xylylenedicyanide is obtained direct by reacting o-xylylene dibromide withpotassium cyanide in 70% yield of pure recrystallised product (J. O.Halford and B. Weissmann, J. Org. Chem. 17, 1649, (1952); E. J. F.Atkinson and J. F. Thorpe, J. Chem. Soc. 91, 1699, (1907)). Theo-xylylene dihalides can in turn be obtained by known processes eitherby direct halogenation of o-xylene or by halomethylation of toluene orbenzyl chloride and separation of o- and p-xylylene dichlorides bydistillation (I. G. Farbenindustrie AG, PB 580 NO. 5:PB 14998 No. 's 94,99 and 100).

By means of the above described process it has become possible to obtainin simple manner and in good yield a number of partly known compoundswhich so far have only been accessible by methods not easy to carry out.It is also possible to obtain new compounds by the novel process, forexample those encompassed by the formulae (1), (3), (5), (7), (9) and(11).

The compounds of formulae (1), (3), (5), (7), (9), (11) and (13) whichcan be obtained according to the present invention can be used asintermediates for the manufacture of fluorescent brighteners,fluorescent dyes, dyes and plastics, after they have been saponified, ifdesired, to give the corresponding 1,4-naphthalenedicarboxylic acidderivatives. Examples of such fluorescent brighteners are cited inGerman Offenlegungsschrift No. 2,237,874 and U.S. Pat. No. 3,709,896,and the use of naphthalene-1,4-dicarboxylic acid for the manufacture ofpolyamides is described in French Pat. No. 876,655.

The conversion of the 1,4-dicyano-substituted compounds of formulae (1),(3), (5), (7), (9), (11) and (13) in the corresponding 1,4-dicarboxylicacids is effected in known manner by alkaline or acid saponification.

In its second feature, the present invention provides a process for themanufacture of bicyclic or tricyclic compounds of formula ##STR15##wherein R₁ ^(v) ' represents a hydrogen, halogen, alkyl, alkoxy,carboxy, sulpho, --SO₂ NR₅ R₆, wherein each of R₅ and R₆ independentlyrepresents hydrogen or alkyl or together they complete a 5- or6-membered heterocyclic ring, alkylsulphonyl, arylsulphonyl, nitro, ortogether with R₂ ^(v) completes a 6-membered aromatic ring or representsthe methylenedioxy radical, R₂ ^(v) represents hydrogen, halogen, alkyl,alkoxy, carboxy, alkylsulphonyl, nitro, or together with R₁ ^(v) 'completes a 6-membered aromatic ring or represents the methylenedioxyradical, R₃ represents hydrogen, halogen or alkyl, and R₄ representshydrogen, halogen or alkyl, which comprises reacting an o-xylylenedicyanide of formula ##STR16## wherein R₁ ^(v) ', R₂ ^(v), R₃ and R₄ areas defined hereinbefore, with glyoxal in the presence of a base and asolvent, and saponifying the resultant reaction product, withoutisolating it, at temperatures above 50° C with an acid or a base.

Suitable bases are inorganic and organic compounds, for example those oflithium, sodium, potassium, rubidium, cesium or ammonium, for examplethe hydroxides, alcoholates or tert. amines, such as lithium, sodium orpotassium hydroxides, sodium or potassium methylate, sodium or potassiumethylate, triethylamine or pyridine.

Suitable solvents are water and organic, preferably water-misciblehigher boiling solvents, for example those that boil between 50° and210° C, such as mono- or polyhydric alcohols, for example propylalcohols, butyl alcohols, ethylene glycol, 1,2-propane diol andglycerol.

Suitable mineral acids for the acid saponification are, for example,hydrochloric acid, sulphuric acid and phosphoric acid as well asaliphatic carboxylic acids, for example acetic and propionic acid. Thesaponification is carried out in the presence of water, preferably atreflux temperature.

Glacial acetic acid can be used as solvent or diluent for cyanides whichare sparingly soluble.

The 1,4-dicarboxylic acid derivatives are obtained in this process ingreat purity and almost colourless. The free dicarboxylic acids can bereacted by methods which are known per se to yield correspondingderivatives, for example salts, esters, amides or halides.

Within the scope of this second feature of the invention, an interestingprocess is that for the manufacture of bicyclic or tricylic compounds offormula ##STR17## wherein R₁ ^(v) " represents hydrogen, halogen, alkyl,carboxy, alkylsulphonyl, arylsulphonyl, nitro, or together with R₂ ^(v)' completes a 6-membered aromatic ring or represents the methylenedioxyradical, R₂ ^(v) ' represents hydrogen, halogen, alkyl, alkoxy,alkylsulphonyl, or together with R₁ ^(v) " completes a 6-memberedaromatic ring or represents the methylenedioxy radical, R₃ representshydrogen, halogen or alkyl, and R₄ represents hydrogen, halogen oralkyl, and of compounds of formula ##STR18## wherein R₁ ^(v) '"represents hydrogen, halogen, alkyl, alkylsulphonyl, arylsulphonyl, ortogether with R₂ ^(v) " completes a 6-membered aromatic ring, R₂ ^(v) "represents hydrogen, halogen, alkyl, alkylsulphonyl, or together with R₁^(v) '" completes a 6-membered aromatic ring, R₃ represents hydrogen,halogen, or alkyl, and R₄ represents hydrogen, halogen or alkyl, whichprocess comprises reacting an o-xylylene dicyanide of formula ##STR19##wherein R₁ ^(v) ", R₂ ^(v) ', R₃ and R₄ are as defined hereinbefore, andof formula ##STR20## wherein R₁ ^(v) '", R₂ ^(v) ", R₃ and R₄ are asdefined hereinbefore, with glyoxal.

Within the scope of this second feature of the invention, a preferredprocess is that for the manufacture of compounds of formula ##STR21##wherein R₁ '^(x) represents hydrogen, halogen or alkyl, or together withR₂ ^(v) '" completes a 6-membered aromatic ring, R₂ ^(v) '" representshydrogen, halogen, alkyl or together with R₁ '^(x) completes a6-membered aromatic ring, R₃ ' represents hydrogen or halogen, and R₄ 'represents hydrogen or halogen, and, in particular, ofnaphthalene-1,4-dicarboxylic acids of formula ##STR22## wherein R₁ ^(x)represents hydrogen, halogen or alkyl, R₂ '^(x) represents hydrogen,halogen or alkyl, and R₃ ' represents hydrogen or halogen, as well asthose of formula ##STR23## wherein R₁ ^(x) ' represents hydrogen orhalogen and R₃ ' represents hydrogen or halogen, which comprisesreacting an o-xylylenedicyanide of formula ##STR24## wherein R₁ '^(x),R₂ ^(v) '", R₃ ' and R₄ ' are as defined hereinbefore, of formula##STR25## wherein R₁ ^(x), R₂ '^(x) and R₃ ' are as definedhereinbefore, or of formula ##STR26## wherein R₁ ^(x) ' and R₃ ' are asdefined hereinbefore, with glyoxal.

Within the scope of the second feature of the present invention, aparticularly preferred process is that for the manufacture of thenaphthalene-1,4-dicarboxylic acid of formula ##STR27## wherein ano-xylylene dicyanide of formula ##STR28## is reacted with glyoxal.

Also of interest within the scope of the present invention are1,4-dicyano-substituted naphthalenes of formula ##STR29## wherein R₇represents halogen, alkyl, alkoxy, carboxy, carbalkoxy, --CONR₅ R₆,wherein each of R₅ and R₆ independently represents hydrogen or alkyl, ortogether they complete a 5- or 6-membered heterocyclic ring, sulpho,--SO₂ NR₅ R₆, in which R₅ and R₆ are as defined hereinbefore,alkylsulphonyl, arylsulphonyl, cyano or nitro, R₂ ^(x) representshydrogen, halogen, alkyl, alkoxy, carboxy, carbalkoxy, --CONR₅ R₆,wherein R₅ and R₆ are as defined hereinbefore, alkylsulphonyl or nitro,R₃ represents hydrogen, halogen or alkyl, and R₄ represents hydrogen,halogen or alkyl, and also 1,4-dicyano-substituted naphthalenes offormula ##STR30## wherein R₇ ' represents halogen, alkyl, alkoxy,carboxy, carbalkoxy, --CONR₅ R₆ in which each of R₅ and R₆ independentlyrepresents hydrogen or alkyl or together they complete a 5- or6-membered heterocyclic ring, alkylsulphonyl, arylsulphonyl, cyano ornitro, R₂ ^(x) ' represents hydrogen, halogen, alkyl, alkoxy oralkylsulphonyl, and R₃ and R₄ are as defined hereinbefore.

Particularly interesting 1,4-dicyano-substituted naphthalenes are thoseof formula ##STR31## wherein R₇ " represents halogen, alkyl,alkylsulphonyl or arylsulphonyl, R₂ ^(x) " represents hydrogen, halogen,alkyl or alkylsulphonyl, R₃ represents hydrogen, halogen or alkyl and R₄represents hydrogen, halogen or alkyl, and also those of formula##STR32## wherein R₇ '" represents halogen or alkyl, R₂ "" representshydrogen, halogen or alkyl, R₃ ' represents hydrogen or halogen, and R₄^(') represents hydrogen or halogen.

Preeminent 1,4-dicyano-substituted naphthalenes are those of formula##STR33## wherein R₇ '" represents halogen or alkyl, R₂ "" representshydrogen, halogen or alkyl and R₃ ' represents hydrogen or halogen, andalso those of formula ##STR34## wherein R₇ ^(v) represents halogen andR₃ ' represents hydrogen or halogen.

Interesting naphthalene derivatives within the scope of the presentinvention are also those of formula ##STR35## wherein Z representscarboxy, carbalkoxy or --CONY₁ Y₂, wherein each of Y₁ and Y₂independently represents hydrogen or alkyl, R₈ represents halogen,alkyl, alkoxy, carboxy, sulpho, --SO₂ NR₅ R₆, in which each of R₅ and R₆independently represents hydrogen or alkyl, or together they complete a5- or 6-membered heterocyclic ring, alkylsulphonyl, alkyl, alkoxy,carboxy, alkylsulphonyl or nitro, R₃ represents hydrogen, halogen oralkyl, and R₄ represents hydrogen, halogen or alkyl.

Particularly interesting naphthalene derivatives are those of formula##STR36## wherein Z is as defined hereinbefore, R₈ ' represents halogen,alkyl, alkoxy, carboxy, alkylsulphonyl, arylsulphonyl or nitro, R₉ 'represents hydrogen, halogen, alkyl, alkoxy, carboxy, alkylsulphonyl ornitro, R₃ represents hydrogen, halogen or alkyl, and R₄ representshydrogen, halogen or alkyl, and also those of formula ##STR37## whereinZ is as defined hereinbefore, R₈ " represents halogen, alkyl,alkylsulphonyl or arylsulphonyl, R₉ " represents hydrogen, halogen,alkyl or alkylsulphonyl, R₃ represents hydrogen, halogen or alkyl, andR₄ represents hydrogen, halogen or alkyl.

Important naphthalene derivatives are those of formula ##STR38## whereinZ is as defined hereinbefore, R₈ '" represents halogen or alkyl, R₉ '"represents hydrogen, halogen or alkyl, R₃ ' represents hydrogen orhalogen, and R₄ ' represents hydrogen or halogen, and, in particular,those of formula ##STR39## wherein Z is as defined hereinbefore, R₈ '"represents halogen or alkyl, R₉ '" represents hydrogen, halogen oralkyl, and R₃ ' represents hydrogen or halogen, and also those offormula ##STR40## wherein Z is as defined hereinbefore, R₉ "" representshalogen, and R₃ ' represents hydrogen or halogen.

The following examples illustrate the invention, the parts being byweight unless otherwise stated.

EXAMPLE 1

15.6 parts of o-xylylene dicyanide and 8.5 parts of glyoxal hydrate(trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% of glyoxal to be liberated,are stirred in 200 parts of methanol. The reaction mixture is treated at15° C, with stirring and under nitrogen, with 11.2 parts of powderedpotassium hydroxide added by small amounts.

After addition of the potassium hydroxide, the reaction mixture isfurther stirred for 15 hours at room temperature and under nitrogen. Theslightly brown colored reaction mixture is then freed from methanolunder vacuum and diluted with 500 parts by volume of water. Theprecipitated crude 1,4-dicyanonaphthalene is filtered off with suctionand washed neutral with water. Yield: 11 parts of 1,4-dicyanonaphthaleneis filtered off with suction and washed neutral with water. Yield: 11parts of 1,4-dicyanonaphthalene (61.8% of theory) in the form ofslightly brown coloured needles; m.p. 175°-185° C.

One recrystallisation from alcohol using 5 parts of activated carbonyields 5.5 parts of the compound ##STR41## as fine needles with amelting point of 204°-205° C.

EXAMPLE 2

78 parts of o-xylylene dicyanide and 42 parts of glyoxal hydrate(trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% of glyoxal to be liberated,are stirred in 400 parts by volume of methanol. The reaction mixture istreated at 0° to 5° C, with stirring and under nitrogen, with 56 partsof powdered potassium hydroxide added by small amounts.

After the addition of potassium hydroxide, stirring is continued for 12hours at 0° to 5° C under nitrogen. The slightly brown coloured reactionmixture is subsequently neutralised with dilute hydrochloric acid, freedfrom methanol under vacuum, and filtered with suction. The filter cakeis washed neutral with water and dried in vacuo. Yield: 88 parts (99% oftheory) of 1,4-dicyanonaphthalene of formula ##STR42## in the form of aslightly brown coloured powder with a melting point of 158° to 168° C.The crude product is taken up in 700 parts by volume of1,2-dichloroethane, treated with 50 parts by weight of sodium chlorideand refluxed. Then 44.5 parts of phosphoroxy chloride in 50 parts byvolume of 1,2-dichloroethane are slowly added dropwise. The reactionmixture is then refluxed for 5 hours, freed from insoluble constituentsby filtration and concentrated to dryness in vacuo. Yield: 67 parts of1,4-dicyanonaphthalene (75% of theory) in the form of a slightly browncoloured crystalline powder with a melting point of 198° -_(")° C.

EXAMPLE 3

21 parts of 4-tert. butyl-1,2-bis-cyanomethyl-benzene and 8.5 parts ofglyoxal hydrate (trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% of glyoxal tobe liberated, are stirred in 80 parts by volume of methanol. Thereaction mixture is further stirred under nitrogen at 0° to 5° C andtreated with 11.2 parts by weight of powdered potassium hydroxide addedby small amounts.

After the addition of potassium hydroxide, stirring is continued for 5hours at 0° to 5° under nitrogen. The slightly brown coloured reactionmixture is subsequently neutralised with dilute hydrochloric acid, freedfrom methanol in vacuo and extracted with methylene chloride. Themethylene chloride extract is washed neutral with water, dried oversodium sulphate and concentrated to dryness in vacuo. Yield: 24 parts ofa yellow oil which is chromatographed over aluminum oxide. Elution withchlorobenzene yields 4 parts (17% of theory) of 6-tert.butyl-1,4-dicyanonaphthalene of formula ##STR43## in the form of whitecrystals with a melting point of 138°-143° C. Two recrystallisationsfrom alcohol yield small white needles which have a melting point of148°- 149° C.

The 4tert. butyl-1,2-bis-cyanomethyl-benzene used as starting materialcan be obtained, for example, as follows: 389 parts of 4-tert.butyl-o-xylene (manufactured in accordance with the particulars of B. W.Larner and A. T. Peters, J. Chem. Soc. 1952, 682) are diluted with 2000parts by volume of carbon tetrachloride and treated with 855 parts ofN-bromosuccinimide and 5 parts of dibenzoyl peroxide. The reactionmixture is slowly heated to reflux until the onset of the exothermicreaction. After the exothermic reaction has subsided, the reactionmixture is kept for 2 hours at reflux and then cooled to roomtemperature. The precipitated succinimide is collected by suctionfiltration and washed with carbon tetrachlorie. Yield: 715 parts of alight brown oil which a gas chromatogram shows to have a content of63.7% of 4-tert. butyl-α,α'-dibromo-o-xylene of formula ##STR44## Theproduct is distilled under a high vacuum. The fraction with a boilingrange of 125°-130° C (0.05 Torr) contains 450 parts of 4-tert.butyl-α,α'-dibromo-o-xylene, with a melting point of 54° -56° C, whichis obtained as small white needles with a melting point of 58°-59° C,after one recrystallisation from methanol.

286 parts of potassium cyanide are dissolved i 1200 parts by volume ofwater and 14 parts of benzyl-tri-n-butyl-ammonium bromide are added asphase transfer catalyst. To the strongly stirred reaction mixture, whichis heated to 95° C, are added dropwise over the course of 15 minutes,after the heating has been removed, 640 parts by weight of molten4-tert. butyl-αα' -dibromo-o-xylene. in

After the addition of the dibromo compound, the reaction mixture isstirred for a further 30 minutes at reflux, rapidly cooled with ice toroom temperature, taken up in methylene chloride, and washed neutralwith water. The methylene chloride layer is dried over sodium sulphateand freed from methylene chloride in vacuo. Yield: 402 parts of ayellowish brown oil which a gas chromatogram shows to have a 70.4%content of 4-tert. butyl-1,2-bis-cyanomethyl-benzene of formula##STR45## The product is distilled under a high vacuum. The fractionwith a boiling range of 166°-170° C (0.08 Torr) contains 230 parts byweight of 4-tert. butyl-1,2-bis-cyanomethyl-benzene with a melting pointof 46°-48° C, which after one recrystallisation from methanol isobtained in the form of small, light yellow needles with a melting pointof 48° C.

EXAMPLE 4

17 parts of 4,5-dimethyl-1,2-bis-cyanomethyl-benzene and 7.8 parts ofglyoxal hydrate (trimer) (3C₂ H₂ O₂.2H₂ O) containing 80% of glyoxal tobe liberated, are stirred in 100 parts by volume of methanol. Thereaction mixture is treated at 0° to 5° C, with stirring and undernitrogen, with 10.5 parts of powdered potassium hydroxide added by smallamounts. After the addition of potassium hydroxide, stirring iscontinued for a further 5 hours at 0° to 5° C under nitrogen. Theslightly brown coloured reaction mixture is subsequently neutralisedwith dilute hydrochloric acid, freed from methanol in vacuo andextracted with methylene chloride. The methylene chloride extract iswashed neutral with water, dried over sodium sulphate and concentratedto dryness in vacuo. Yield: 18 parts of a brown oil which ischromatographed over aluminium oxide. Elution with chlorobenzene yields6.5 parts (34% of theory) of 6,7-dimethyl-1,4-di-cyanonaphthalene offormula ##STR46## in the form of white crystals with a melting point of212°-220° C. Two recrystallisations from alcohol yield small whiteneedles with a melting point of 225°-227° C.

The 4,5-dimethyl-1,2-cyanomethyl-benzene used as starting material canbe obtained for example as follows according to the reaction scheme:##STR47##

A) 5,6 dimethyl-1,4-dihydro-phthalic acid dimethyl ester (I)

A trace of hydroquinone is added first to 142 parts ofacetylenedicarboxylic acid dimethyl ester and then 90 parts of2,3-dimethyl-1,3-butadiene are slowly added dropwise. The temperature ofthe exothermic reaction may not exceed 70° C. The reaction mixture issubsequently kept for 2 hours at reflux (70° C) and then cooled to roomtemperature. A slightly yellow coloured oil is obtained which a gaschromatogram shows to have a 90.9% content of5,6-dimethyl-1,4-dihydrophthalic acid dimethyl ester (I). The product isfurther reacted without purification.

B) 4,5-dimethyl-phthalic acid dimethyl ester (II)

232 parts of the 5,6-dimethyl-1,4-dihydro-phthalic acid dimethyl ester(I) obtained in A) are first freed from readily volatile constituents invacuo and then diluted with 400 parts by volume of acetic anhydride.Then 133 parts of selenium dioxide are slowly added by small amounts tothe reaction mixture, which is heated to 100° C, and the temperaturerises to 130° C without external application of heat. The reactionmixture is subsequently refluxed for 3 hours and freed from aceticanhydride in vacuo. The residue is taken up in methylene chloride, thesolution is freed from precipitated selenium by filtration, then freedfrom acid constituents with a saturated aqueous sodium bicarbonatesolution, washed neutral with water, dried over sodium sulphate andconcentrated to dryness in vacuo. Yield: 230 parts of a yellowish brownoil which a gas chromatogram shows to have a 94% content of4,5-dimethyl-phthalic acid dimethyl ester (II). The product is distilledunder a high vacuum. The fraction with a boiling range of 116°-120° C(0.04 Torr) contains 174 parts (78% of theory) of 4,5-dimethyl-phthalicacid dimethyl ester (II) with a melting point of 54°-55° C.

C) 4,5 -Dimethyl-phthalic alcohol

58.5 parts of lithium aluminium hydride are suspended at roomtemperature, in an atmosphere of nitrogen, in 1500 parts by volume ofanhydrous tetrahydrofuran. To the stirred suspension is added dropwisein the course of 2 hours a solution of 173 parts of4,5-dimethyl-phthalic acid dimethyl ester (II) in 1000 parts by volumeof anhydrous tetrahydrofuran. The reaction mixture is refluxed for 3hours and then cooled to 10° C. Then 59 parts by volume of water, 59parts by volume of 15% sodium hydroxide solution and 177 parts by volumeof water are added in succession to the stirred, ice-cold reactionmixture. Stirring is continued for 1 hour, then the salts are filteredoff and washed with tetrahydrofuran. The filtrate is dried over sodiumsulphate and concentrated in vacuo to dryness. Yield: 102 parts (83% oftheory) of 4,5-dimethyl-phthalic alcohol (II) in the form of a whitecrystalline powder with a melting point of 100°-103° C. Aftersublimation under a high vacuum, it is obtained in the form of whitecrystals with a melting point of 103° -104° C.

D) 4,5-Dimethyl-α,α'-dibromo-o-xylene (IV)

A solution of 165 parts of phosphorus tribromide in 500 parts by volumeof methylene chloride is added dropwise in the course of 2 hours at roomtemperature to a solution of 100 parts of 4,5-dimethyl-phthalic alcoholin 1000 parts by volume of methylene chloride, in the process of whichthe temperature may not exceed 35° C. The reaction mixture is stirredfor a further 3 hours at room temperature, then cooled to 10° C anddiluted with 500 parts of water in the course of 10 minutes. Thetemperature remains below 25° C. The methylene chloride layer isseparated, freed from acid constituents with 2 normal sodium carbonatesolution, dried over sodium sulphate and concentrated to dryness invacuo. Yield: 168 parts (95% of theory) of4,5-dimethyl-α-α'-di-bromo-o-xylene (IV) in the form of a whitecrystalline powder with a melting point of 116°-120° C which is obtainedafter one recrystallisation from alcohol in the form of small whiteneedles with a melting point of 119°-120° C.

E) 4,5-Dimethyl-1,2-bis-cyanomethyl-benzene (V)

47 parts of potassium cyanide are dissolved in 100 parts by volume ofwater. The solution is diluted with 300 parts by volume of ethanol andrefluxed. The 95 parts of powdered 4,5-α,α'-dibromo-o-xylene are addedby small amounts in the course of 15 minutes while the reaction mixtureremains under reflux without the application of heat. The reactionmixture is subsequently refluxed for 1 hour, rapidly cooled with ice,acidified with 2 normal hydrochloric acid and freed from ethanol invacuo. The aqueous suspension is filtered with suction and the filtercake is washed neutral with water. Yield: 55 parts (91% of theory) of4,5-dimethyl-1,2-bis-cyanomethyl-benzene (V) in the form of a yellowcrystalline powder with a melting point of 95°-102° C. After onerecrystallisation from alcohol with activated carbon it is obtained inthe form of small, fine, pale yellow needles, which, after sublimationin a high vacuum, have a melting point of 103°-104° C.

EXAMPLE 5

12 parts of 3,4,5,6-tetrachloro-1,2-bis-cyanomethyl-benzene and 12 partsby volume of a 30% aqueous glyoxal solution are stirred in 240 parts ofmethanol. With stirring and under nitrogen, 4.8 parts of powderedpotassium hydroxide are added to the reaction mixture by small amountsat -10° C and the temperature rises to -1° C.

After the addition of potassium hydroxide, stirring is continued for afurther 5 hours at -10° C under nitrogen. The slightly brown colouredreaction mixture is subsequently neutralised with 2 normal hydrochloricacid, freed from methanol in vacuo and filtered with suction. The filtercake is washed neutral with water. Yield: 9 parts (70% of theory) of5,6,7,8-tetrachloro-1,4-dicyanonaphthalene of formula ##STR48## in theform of a light brown crystalline powder with a melting point of215°-220° C. Small white needles which melt at 221°-222° C are obtainedafter two recrystallisations from alcohol with activated carbon.

The 3,4,5,6-tetrachloro-1,2-bis-cyanomethyl-benzene used as startingmaterial can be obtained, for example, as follows:

160 parts of 3,4,5,6-tetrachloro-α,α'-dibromo-o-xylene are dissolved hotin 300 parts by volume of benzene. The solution is diluted with 600parts by volume of methanol and refluxed. Then 41.2 parts of sodiumcyanide are added by small amounts in the course of 15 minutes to thestrongly stirred reaction mixture, which is further stirred for 1 hourunder reflux, rapidly cooled to 0° C with ice and acidified with 400parts by volume of 2 normal hydrochloric acid. The resultant yellowsuspension is freed from methanol and benzene in vacuo, filtered withsuction, and the filter cake is washed neutral with water. Yield: 110parts (94% of theory) of 3,4,5,6-tetrachloro-1,2-bis-cyanomethyl-benzeneof formula ##STR49## in the form of a yellow crystalline powder whichmelts at 182°-196° C. Two recrystallisations from chlorobenzene with 25parts of activated carbon yields 32 parts of yellow needles with amelting point of 227°-229° C.

The 3,4,5,6-tetrachloro-α,α'-dibromo-o-xylene used as starting materialwas obtained in accordance with the particulars of German Auslegeschrift1.568.607 and U.S. Pat. No. 2,702,825.

EXAMPLE 6

20 parts of 2,3-bis-cyanomethyl-naphthalene and 8.5 parts of glyoxalhydrate (trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% of glyoxal to beliberated, are stirred in a mixture of 300 parts by volume of methanoland 50 parts by volume of dimethyl sulphoxide. With stirring and undernitrogen, 11.2 parts of powdered potassium hydroxide are added by smallamounts to the reaction mixture at 0° C to 5° C. After the addition ofthe potassium hydroxide, stirring is continued for 24 hours at roomtemperature under nitrogen. The slightly brown coloured reaction mixtureis subsequently acidified with 200 parts by volume of 2 normalhydrochloric acid, freed from methanol in vacuo, diluted with 100 partsby volume of water and filtered with suction. The filter cake is washedneutral with water. Yield: 22.7 parts (100% of theory) of1,4-dicyano-anthracene of formula ##STR50## in the form of a browncrystalline powder with a melting point of 190°-225° C.

The crude product is taken up in methylene chloride and the solution isfreed from insoluble constituents by filtration, decolourised withactivated carbon and recrystallised from chlorobenzene. Tworecrystallisations from chlorobenzene yield yellow needles with amelting point of 264°-265° C. The 2,3-bis-cyanomethyl-naphthalene wasobtained from 2,3-dimethyl-naphthalene according to the particulars ofW. Ried and H. Bodem, Ber. 89 708-12 (1956).

EXAMPLE 7

31.2 parts of o-xylylene dicyanide and 17 parts of glyoxal hydrate(trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% of glyoxal to be liberated,are stirred in 200 parts by volume of methanol. With stirring and undernitrogen, 21.6 parts of powdered sodium methylate are added to thereaction mixture by small amounts at 0° to 5° C.

After addition of sodium methylate, stirring is continued for 5 hours at0° to 5° C under nitrogen. The slightly brown coloured reaction mixtureis subsequently diluted with 200 parts of ethanol, treated with 56 partsof powdered potassium hydroxide and slowly heated to 190° C undernitrogen, in the process of which the methanol is distilled off andammonia escapes at 80° C. After it has been stirred for 15 hours at185°-190° C under nitrogen, the reaction mixture is cooled to 100° C anddiluted with 1000 parts by volume of water. The dark brown, clearsolution is decolourised in a steam bath with 15 parts of activatedcarbon and acidified with 150 parts by volume of concentratedhydrochloric acid. The precipitated acid is filtered off hot withsuction and the filter cake is washed neutral with water. Yield: 30parts of naphthalene-1,4-dicarboxylic acid (69% of theory) in the formof a pale yellow crystalline powder with a melting point of 310°-315° C.

EXAMPLE 8

The reaction is carried out under the same conditions as described inExample 7, except that 22.4 parts of powdered potassium hydroxide areused instead of 21.6 parts of sodium methylate.

Yield: 29 parts of naphthalene-1,4-dicarboxylic acid (67% of theory) inthe form of a pale yellow crystalline powder with a melting point of310°-315° C.

EXAMPLE 9

38 parts of 4-chloro-1,2-bis-cyanomethyl-benzene and 17 parts of glyoxalhydrate (trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% of glyoxal to beliberated, are stirred in 150 parts by volume of methanol. With stirringand under nitrogen, 16 parts of powdered sodium hydroxide are added tothe reaction mixture by small amounts at 0° to 5° C.

After the addition of sodium hydroxide, stirring is continued for 5hours at 0° to 5° C under nitrogen. The slightly brown coloured reactionmixture is subsequently treated with 200 parts by volume of 80%sulphuric acid and 80 parts by volume of glacial acetic acid and slowlyheated to 140° C under nitrogen while distilling off the methanol. Afterit has been stirred for 5 hours at 140°-150° C under nitrogen, thereaction mixture is cooled to 150° C and diluted with 500 parts ofwater. The precipitate is filtered off with suction, washed neutral withwater and taken up in 500 parts by volume of water. Then 60 parts byvolume of 30% sodium hydroxide solution are added and the dark brownsolution is decolourised in a steam bath with 15 parts of activatedcarbon and acidified with 150 parts by volume of concentratedhydrochloric acid. The precipitated acid is filtered off hot and thefilter cake is washed neutral with water. Yield: 34 parts of6-chloro-naphthalene-1,4-dicarboxylic acid (68% of theory) of formula##STR51## in the form of slightly brown crystalline powder with amelting point of 278°-280° C.

Small, pale yellow needles are obtained after one recrystallisation fromglacial acetic acid; melting point 281°-283° C.

The 4-chloro-1,2-bis-cyanomethyl-benzene used as starting material wasobtained according to the particulars of A.S. Dey, A. Rosowsky and E. J.Modest, J. Org. Chem. 1970 536-9.

EXAMPLE 10

106 parts of 4-tert. butyl-1,2-bis-cyanomethyl-benzene and 42 parts ofglyoxal hydrate (trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% of glyoxal tobe liberated, are stirred in 400 parts by volume of methanol. Withstirring and under nitrogen, 56 parts of potassium hydroxide are addedto the reaction mixture by small amounts at 0° to 5° C.

After the addition of potassium hydroxide, stirring is continued for 5hours at 0° to 5° C. The slightly brown coloured reaction mixture issubsequently diluted with 250 parts of ethylene glycol and then, afteraddition of 84 parts of powdered potassium hydroxide, slowly heated to190° C under nitrogen while the methanol is distilled off and ammoniaescapes at 80° C. After it has been stirred for 5 hours at 185° to 190°C under nitrogen, the reaction mixture is worked up as described inExample 7.

Yield: 89 parts of 6-tert. butyl-naphthalene-1,4-dicarboxylic acid (65%of theory) of formula ##STR52## in the form of a light brown crystallinepowder with a melting point of 276°-279° C.

Small, pale yellow needles with a melting point of 286°-288° C areobtained after one recrystallisation from glacial acetic acid withactivated carbon.

The 4-tert. butyl-1,2-bis-cyanomethyl-benzene can be obtained asdescribed in Example 3.

EXAMPLE 11

18.4 parts of 4,5-dimethyl-1,2-bis-cyanomethyl-benzene and 8.4 parts ofglyoxal hydrate (trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% of glyoxal tobe liberated, are stirred in 100 parts by volume of methanol. Withstirring and under nitrogen, 11.2 parts of powdered potassium hydroxideare added to the reaction mixture by small amounts at 0° to 5° C. Afterthe addition of potassium hydroxide, stirring is continued for 5 hoursat 0° to 5° C under nitrogen. The slightly brown coloured reactionmixture is subsequently diluted with 100 parts by volume of ethyleneglycol and then, after addition of 28 parts of potassium hydroxide,heated slowly to 190° C under nitrogen while the methanol is distilledoff and ammonia escapes at 80° C. After it has been stirred for 5 hoursat 185° to 190° C under nitrogen, the reaction mixture is worked up asdescribed in Example 7 to yield 7.5 parts of6,7-dimethyl-naphthalene-1,4-dicarboxylic acid (31% of theory) offormula ##STR53## in the form of slightly brown crystalline powder witha melting point of 268°-280° C.

Small, pale yellow needles with a melting point of 288°-291° C areobtained after one recrystallisation from glacial acetic acid withactivated carbon.

The 4,5-dimethyl-1,2-bis-cyanomethyl-benzene used as starting materialcan be obtained as described in Example 4.

EXAMPLE 12

12 parts of 3,4,5,6-tetrachloro-1,2-bis-cyanomethyl-benzene and 12 partsby volume of a 30% aqueous glyoxal solution are stirred in 240 parts ofmethanol. With stirring and under nitrogen, 4.8 parts of powderedpotassium hydroxide are added to the reaction mixture by small amountsat -10° C and the temperature rises to -1° C.

After the addition of potassium hydroxide, stirring is continued for 5hours at -10° C under nitrogen. The slightly brown coloured reactionmixture is subsequently treated with 80 parts by volume of 80% sulphuricacid and 15 parts by volume of glacial acetic and slowly heated to 140°C under nitrogen while distilling off the methanol. After it has beenstirred for 5 hours at 140° to 150° C under nitrogen, the reactionmixture is cooled to 100° C and diluted with 200 parts by volume ofwater. The precipitate is filtered off with suction, washed neutral withwater and dried under vacuum at 100° C.

Yield: 12 parts of 5,6,7,8-tetrachloro-naphthalene-1,4-dicarboxylic acid(85% of theory) of formula ##STR54## in the form of a brownish blackcrystalline powder with a melting point of 285°-290° C.

The crude product is taken up in 200 parts by volume of water and 30parts by volume of aqueous 30% sodium hydroxide solution are added tothe solution. The dark brown solution is decolourised in a steam bathwith 5 parts of activated carbon and acidified with 100 parts by volumeof concentrated hydrochloric acid. The precipitated acid is filtered offhot and the filter cake is washed neutral with water. Tworecrystallisations from glacial acetic acid yields 2 parts of smallwhite needles with a melting point of 319°-321° C.

The 3,4,5,6-tetrachloro-1,2-bis-cyanomethyl-benzene used as startingmaterial can be obtained as described in Example 5.

EXAMPLE 13

40 parts by weight of 2,3-bis-cyanomethyl-naphthalene and 17 parts byweight of glyoxal hydrate (trimer) (3C₂ H₂ O₂.2H₂ O), containing 80% ofglyoxal to be liberated, are stirred in a mixture of 600 parts by volumeof methanol and 100 parts by volume of dimethyl sulphoxide. Withstirring and under nitrogen, 22.4 parts of powdered potassium hydroxideare added to the reaction mixture by small amounts at 0° to 5° C. Afterthe addition of potassium hydroxide, stirring is continued for 24 hoursat room temperature under nitrogen. The slightly brown coloured reactionmixture is subsequently acidified with 200 parts by volume of 2 normalhydrochloric acid, freed from methanol in vacuo, diluted with 200 partsby volume of water, filtered with suction and the filter cake is washedneutral with water.

The moist filter cake is taken up in 300 parts by volume of ethyleneglycol and the solution, after addition of 36 parts of powderedpotassium hydroxide, is slowly heated to 180° C under nitrogen while themethanol is distilled off and ammonia escapes at 80° C. After it hasbeen stirred for 5 hours at 170° to 180° C under nitrogen, the reactionmixture is worked up as described in Example 7. Yield: 29 parts ofanthracene-1,4-dicarboxylic acid (55% of theory) of formula ##STR55## inthe form of a yellowish red crystalline powder with a melting point of301°-302° C.

Small, yellowish red needles with a melting point of 303°-304° C areobtained after one recrystallisation from glacial acetic acid withactivated carbon.

The 2,3-bis-cyanomethyl-naphthalene used as starting material wasobtained according to the particulars of W. Ried and H. Bodem, Ber. 89,708-12 (1956).

15 parts of anthracene-1,4-dicarboxylic acid are stirred in 200 parts byvolume of chlorobenzene and 0.5 part by volume of dimethylformamide. Thereaction mixture is refluxed and treated dropwise with 20 parts ofthionyl chloride, whereupon a clear solution is obtained. Afterrefluxing for 1 hour, excess thionyl chloride is distilled off withabout 100 parts by volume of chlorobenzene and the reaction mixture iscooled to room temperature. Then 100 parts by volume of ethanol areadded and the clear solution is refluxed for a further hour andconcentrated to dryness in vacuo. One recrystallisation from ethanolwith activated carbon yields 12 parts of anthracene-1,4-dicarboxylicacid diethyl ester (66% of theory) of formula ##STR56## in the form oflong yellow needles with a melting point of 99°-100° C.

What I claim is:
 1. A process for the manufacture of1,4-dicyano-substituted bicyclic or tricyclic compounds of formula##STR57## wherein R₁ represents hydrogen, halogen, alkyl, alkoxy,carboxy, carbalkoxy, --CONR₅ R₆, wherein each of R₅ and R₆ independentlyrepresents hydrogen or alkyl, or together they complete a 5- or6-membered heterocyclic ring, sulpho-, --SO₂ NR₅ R₆, in which R₅ and R₆are as defined hereinbefore, alkylsulphonyl, arylsulphonyl, cyano,nitro, or together with R₂ completes a 6-membered aromatic ring orrepresents the methylenedioxy radical, R₂ represents hydrogen, halogen,alkyl, alkoxy, carboxy, carbalkoxy, --CONR₅ R₆, wherein R₅ and R₆ are asdefined hereinbefore, alkylsulphonyl, nitro, or together with R₁completes a 6-membered aromatic ring or represents the methylenedioxyradical, R₃ represents hydrogen, halogen or alkyl and R₄ representshydrogen, halogen or alkyl, which process comprises reacting an o-xylenedicyanide of formua ##STR58## wherein R₁, R₂, R₃ and R₄ are as definedhereinbefore, with glyoxal, in the presence of a base and a solvent, attemperatures below 50° C.
 2. A process according to claim 1 for themanufacture of 1,4dicyano-substituted bicyclic or tricyclic compounds offormula ##STR59## wherein R₁ ' represents hydrogen, halogen, alkyl,alkoxy, carboxy, carbalkoxy, --CONR₅ R₆, wherein each of R₅ and R₆independently represents hydrogen or alkyl, or together they complete a5- or 6-membered heterocyclic ring, alkyl-sulphonyl, arylsulphonyl,cyano, nitro, or together with R₂ ' completes a 6-membered aromatic ringor represents the methylenedioxy radical, R₂ ' represents hydrogen,halogen, alkyl, alkoxy, alkylsulphonyl, or together with R₁ ' completesa 6-membered aromatic ring or represents the methylenedioxy radical, andR₃ and R₄ are as defined in claim 1, which process comprises reacting ano-xylene dicyanide of formula ##STR60## wherein R₁ ', R₂ ', R₃ and R₄are as defined hereinbefore, with glyoxal.
 3. A process according toclaim 1 for the manufacture of 1,4-dicyano-substituted bicyclic ortricyclic compounds of formula ##STR61## wherein R₁ " representshydrogen, halogen, alkyl, alkylsulphonyl, arylsulphonyl, or togetherwith R₂ " completes a 6-membered aromatic ring, R₂ " representshydrogen, halogen, alkyl, alkylsulphonyl, or together with R₁ "completes a 6-membered aromatic ring, R₃ represents hydrogen, halogen oralkyl, and R₄ represents hydrogen, halogen or alkyl, which processcomprises reacting an o-xylylene dicyanide of formula ##STR62## whereinR₁ ", R₂ ", R₃ and R₄ are as defined hereinbefore, with glyoxal.
 4. Aprocess according to claim 1 for the manufacture of1,4-dicyano-substituted bicyclic or tricyclic compounds of formula##STR63## wherein R₁ "' represents hydrogen, halogen or alkyl, ortogether with R₂ "' completes a 6-membered aromatic ring, R₂ "'represents hydrogen, halogen or alkyl, or together with R₁ "' completesa 6-membered aromatic ring, R₃ ' represents hydrogen or halogen and R₄ 'represents hydrogen or halogen, which process comprises reacting ano-xylylene dicyanide of formula ##STR64## wherein R₁ "' , R₂ "', R₃ 'and R₄ ' are as defined hereinbefore, with glyoxal.
 5. A processaccording to claim 1 for the manufacture of 1,4-dicyano-substitutednaphthalenes of formula ##STR65## wherein R₁ "" represents hydrogen,halogen or alkyl, R₂ ""represents hydrogen, halogen or alkyl, and R₃ 'represents hydrogen or halogen, which process comprises reacting ano-xylylene dicyanide of formula ##STR66## wherein R₁ "", R₂ "", and R₃ 'are as defined hereinbefore, with glyoxal.
 6. A process according toclaim 1 for the manufacture of 1,4-dicyano-substituted naphthalenes offormula ##STR67## wherein R₁ ^(V) represents hydrogen or halogen and R₃' represents hydrogen or halogen, which comprises reacting an o-xylylenedicyanide of formula ##STR68## wherein R₁ ^(V) and R₃ ' are as definedhereinbefore, with glyoxal.
 7. A process according to claim 1 for themanufacture of 1,4-dicyanonaphthalene of formula ##STR69## whichcomprises reacting o-xylylene dicyanide of formula ##STR70## withglyoxal.